1. Field
Example embodiments relate to memory devices having a carbon nanotube and methods of manufacturing the same. More particularly, example embodiments relate to memory devices having a carbon nanotube as a resistance switch and methods of manufacturing the same.
2. Description of the Related Art
Semiconductor devices having high data transmission speed are desired for many applications. One way of increasing the data transmission speed of a semiconductor device may be to increase an integration degree such that a chip includes a plenty of cells. A design rule for wirings in semiconductor chips has been reduced to a nanometer scale to increase the integration degree of the cells. However, reducing the design, rule of the wiring may cause some technical problems. For example, a specific resistance of a wiring may exponentially increase depending on a decrease of a critical dimension of the wiring. Hillocks caused by electro-migrations (which may increase the likelihood of cuts in the metal wiring) may occur. Formation of a diffusion barrier layer may become difficult in some applications. To overcome these problems, techniques for forming a wiring using a carbon nanotube have been investigated.
A carbon nanotube has a one-dimensional quantum-wire structure. The carbon nanotube also has electrical characteristics such as a quantum transport in one dimension. The carbon nanotube may have a good current density characteristic, as being compared with a metal wiring. For example, it has been experimentally proved that the carbon nanotube may have a current density of about 109 A/cm2, and may exhibit ballistic transport characteristics.
A memory device having a horizontal or vertical structure in which a carbon nanotube wiring may be used as a switching element has been researched by some companies (e.g., Nantero, Samsung Electronics, etc.). However, operational malfunctions due to a leakage current may frequently occur in such a memory device.